fix: Prevent conflicting filename for sourcemaps

[pioug]

Fixes #238. Related to #215 and maybe #248.

Changes proposed in this pull request:

• Rename file inside sourcemaps to avoid Rollup error

I think Rollup doesn't like that the Vue plugin outputs multiple sourcemaps with the same names because it triggers the following error when running rollup --watch:

 } else if ( 
 	traced.source.content != null && 
 	sourcesContent[sourceIndex] !== traced.source.content 
 ) { 
 	return error({ 
 		message: `Multiple conflicting contents for sourcemap source ${traced.source.filename}` 
 	}); 
 } 

https://github.com/rollup/rollup/blob/0ffbe94981a1201da851eb6001cce7bb5b8efb20/src/utils/collapseSourcemaps.ts#L79-L86

I have a dumb patch to propose, hoping to bring attention to the problem and get help to solve it properly. It's reproducing on v5 and also the new v6. I think since the sourcemaps have been introduced.

I ignore whether renaming the sourcemaps affects other parts of the build. So I choose to leave the sourcemaps for script untouched, while renaming the others (which are less critical, at least for my usage).

I read in one of the comments that it may be due to @vue/compiler-sfc... but I prefer to ask for help first before digging into that too 😅 I can write the tests once we are certain about the solution.

/ping @znck 🙏

[danielvy]

I'm running into the same issue.

This makes the workflow pretty tedious as I need to enable/disable source maps every time or exit rollup's watch and rebuild the project.

Any idea if/when this is going to be fixed?